The present invention relates generally to apparatus for forming concrete or other flowable paving material into a paved surface and, more particularly, to such a paving apparatus of the self propelled type for continuous slip-form paving of roadways, sidewalks and like concrete pavement surfaces.
Self-propelled construction vehicles and other construction equipment of diverse types are well known. One type of such construction equipment are so-called slip-form paving machines essentially adapted to continuously form concrete or another flowable paving material along the ground or other base surface, for example, to form a roadway. Diverse forms of such machines have been described in prior patents, representative examples of which may be found in U.S. Pat. Nos. 3,175,478; 3,264,958; 3,637,026; 3,771,892; 3,970,405; 4,197,032; 4,360,293; 4,925,340; 4,948,292; 5,044,820 and 5,590,977.
Conventionally, it is commonplace for paving equipment of this type to support the machine frame on a plurality of drivable transport assemblies, such as so-called crawler track assemblies, adapted to facilitate steerable driving of the paving machine over substantially any ground surface along which a roadway or like surface is to be paved. The frame of the machine is equipped with various devices and mechanisms to perform various functions of the paving operation, including typically an auger or other suitable mechanism for distributing the paving material laterally across the front of the machine, followed by a vertically disposed plate or like structural member, commonly referred to as a strike-off plate, positioned with a lower edge thereof at a desired elevation with respect to the ground surface to be paved to control the amount of paving material passing thereunder and thereby to initially form the material generally as a slab of the desired thickness, and then followed by a substantially horizontally disposed undersurface, commonly referred to as a screed, for purposes of leveling and finishing the concrete material.
In basic operation, a continuous supply of concrete or other suitable paving material is deposited in front of the paving machine between its transport assemblies as the machine is driven over the intended path of the pavement surface, with the auger mechanism initially distributing the paving material laterally, after which the lower edge of the plate xe2x80x9cstrikes offxe2x80x9d a rough slab form of a desired thickness of the concrete material which then is more precisely spread, leveled and finished by vibration devices followed by the screed.
Once such a paving machine is under operation, it is a relatively simple matter to maintain ongoing operation on a substantially continuous basis, absent any malfunctions in the machinery itself, merely by maintaining a sufficient supply of concrete in front of the advancing machine. However, the initial start-up of a paving operation, including beginning operation at the start of each work day or otherwise after a period of sufficiently extended inactivity in the paving operation by which the concrete of a previously paved section of roadway has solidified and begun to cure, requires special efforts and can be much more problematic.
Specifically, the initial start-up of a slip-form paving operation, especially when continuing the paving of a previously formed section of pavement, requires that a sufficient starting supply of concrete be deposited not only in front of the auger mechanism and the strike-off plate but also therebehind beneath the screed fully up to the previously formed section of pavement, so as to ensure that there will be no interruption in the continuity nor the quality of the pavement slab. Generally, the only reliable way of accomplishing start-up of a slip-form paving machine under such circumstances is to position the machine immediately above the previously formed section of pavement and then to have workers manually shovel and preliminarily level a sufficient quantity of new wet concrete beneath and behind the auger mechanism, the strike-off plate and the screed, in addition to depositing a supply of concrete in front of the auger mechanism, whereupon operation of the machine can begin. This process is not only labor-intensive, time-consuming, expensive and inefficient, it is also difficult to ensure that the starting portion of the new section of pavement is of comparable quality and uniformity to that of the previously-formed section.
It is accordingly an object of the present invention to provide an improved slip-form paving apparatus which will address and overcome the disadvantages of the known paving apparatus as discussed above. More particularly, it is an object of the present invention to provide a slip-form paving apparatus which will better facilitate the deposition of a supply of concrete beneath the apparatus for starting up a new paving operation.
Briefly summarized, the present invention is basically applicable to any slip-form paving apparatus having a frame supported on a steerable self-propelled transport arrangement with a pavement forming assembly or like means disposed on the frame at a forward side thereof. In accordance with the present invention, the pavement forming assembly is movable with respect to the frame between an operative position disposed relative to a ground surface to be paved for distributing and forming a paving material on the ground surface generally into a desired form of pavement and an inoperative position disposed at a greater elevation relative to the ground surface than in the operative position for permitting access beneath the frame during an initial start-up of the apparatus so as to enable a starting quantity of the paving material to be readily deposited thereat.
In a preferred embodiment, the pavement forming assembly comprises a spreading mechanism or like means for distributing paving material across the forward side of the frame, e.g., an auger mechanism, a plow-type spreader, or the like, and a strike-off member or like means for generally leveling the pavement material on the ground surface. The spreading mechanism and the strike-off member, such as a strike-off plate, are integrally mounted pivotably to the frame for pivoting movement between the inoperative and operative positions. Thus, with the pavement forming assembly pivoted or otherwise moved into its inoperative position, workers have ready access to deposit and preliminarily work a starting supply of concrete or other paving material beneath the paving apparatus behind the normal operative disposition of the spreading mechanism and the strike-off member, after which the pavement forming assembly may be pivotably moved into its operative position for beginning the paving operation.
Other details, features and advantages of the present invention will be described and understood from a detailed description of a preferred embodiment of the invention set forth below with reference to the accompanying drawings.